Apparatus and Methods for Color Displays

• US 20110273495A1
• Filed: 01/20/2010
• Published: 11/10/2011
• Est. Priority Date: 01/21/2009
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Seetzen, Helge, Davies, Trevor, Ward, Gregory J.
• Granted Patent: US 8,711,085 B2
• Time in Patent Office: Days
• US Class Current: 345/694
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A display incorporates both narrow-band light emitters and broadband light emitters. The light emitters are controlled to display images according to image data. The narrow-band light emitters can be used to provide highly saturated primary colors. Light from the broadband light sources may be mixed with the broadband light. This can reduce metamerism failures arising from variations in the characteristics of the eyes of observers.

Claims

1. A display comprising:

a spatial light modulator comprising an array of controllable pixels, each pixel comprising a plurality of sub-pixels;

a plurality of primary color light-emitting elements arranged to illuminate the spatial light modulator with light of a plurality of colors;

at least one broadband light-emitting element having a spectral bandwidth at half maximum of at least 150 nm and being arranged to illuminate the spatial light modulator; and

a controller that is configured for;

estimating a light field at the spatial light modulator, wherein the light field is generated by one or more of the light-emitting elements;

determining a driving signal for each sub-pixel based on a value of the estimated light field at a location of the sub-pixel; and

,

applying the driving signals to the sub-pixels.

2. A display according to claim 1 wherein the controller is configured for estimating separate light fields for spectral ranges corresponding to each color of the sub-pixels.

3. A display according to claim 1 wherein the controller is configured for estimating the light field at the spatial light modulator by determining and summing light from individual contributing light-emitting elements for a plurality of locations on the spatial light modulator.

4. A display according to claim 1 wherein the spatial light modulator comprises an LCD panel.

5. A display according to claim 1 comprising means for independently spatially modulating a distribution of the primary color light of each of the plurality of colors over the spatial light modulator.

6. A display according to claim 1 comprising means for spatially modulating a distribution of the broadband light over the spatial light modulator.

7. A display according to claim 1 comprising a backlight wherein the plurality of primary color light-emitting elements are arrayed on the backlight.

8. A display according to claim 1 wherein the broadband light-emitting element is controllable to alter an amount of the light at a location on the spatial light modulator and the controller is connected to receive image data and configured to:

determine from the image data a chromaticity corresponding to the location on the spatial light modulator and, based at least in part on the chromaticity, control the amount of the broadband light at the location on the spatial light modulator.

9. A display according to claim 8 wherein the controller is configured to determine, from the chromaticity determined from the image data corresponding to a location on the spatial light modulator, a saturation index for each of a plurality of primary colors, wherein the saturation index for each primary color is a measure of how closely light of the primary color alone matches the chromaticity, and, based on the saturation indices, control the amount of the broadband light at the location on the viewing screen.

10. A display according to claim 9 wherein the controller is configured to determine whether the chromaticity falls within a region of chromaticity values, wherein the region corresponds to, or is a region within, a gamut that can be accurately reproduced if the spatial light modulator is illuminated only by light from the at least one broadband light-emitting element, and, if so, suppress illumination of the location with the primary color light.

11. A display according to claim 10 wherein the primary color light-emitting elements comprise organic LEDs controllable to alter an amount of the primary color light at the location on the spatial light modulator.

12. A display according to claim 1 wherein

the plurality of primary color light-emitting elements are arranged in a plurality of groups of primary color light-emitting elements;

and

the controller is configured to control the pixels of the spatial light modulator and the primary color light-emitting elements and the at least one broadband light-emitting element according to image data defining an image to be displayed.

13. A display according to claim 12 wherein the primary color light-emitting elements and the at least one broadband light-emitting element are independently controllable.

14. A display according to claim 13 wherein:

the display comprises a backlight and the plurality of primary color light-emitting elements and the at least one broadband light-emitting element are arrayed on the backlight, and each pixel in the spatial light modulator is illuminated by at least one broadband light-emitting element and at least one primary color light-emitting element of each primary color.

15. A display according to claim 14 wherein:

the backlight comprises separate arrays of light emitting elements of one or more different types, and patterns of light emitted by the separate arrays are combined upstream from or at the spatial light modulator; and

the separate arrays are arranged on a plurality of separate planes.

16. A display according to claim 15 wherein the light-emitting elements of two or more of the types of the primary color light-emitting elements are interspersed in one array and light issuing from the array is combined with light from one or more other types of the primary color light-emitting elements before passing to the spatial light modulator.

17. A method for displaying a color image on a display, the display comprising a plurality of controllable primary color light-emitting elements capable of emitting light of a plurality of primary colors defining a color gamut, and one or more broadband light-emitting elements having a spectral bandwidth at half maximum of at least 150 nm, the method comprising, for each of a plurality of areas of the image to be displayed:

determining a representative chromaticity of the area;

determining if the representative chromaticity is in a defined region of chromaticity values, wherein the region corresponds to, or is a region within, a gamut that can be accurately reproduced if the spatial light modulator is illuminated only by light from the one or more broadband light-emitting elements;

if the representative chromaticity is not in the defined region of chromaticity values, then establishing driving signals for the primary color light-emitting elements that correspond to the area;

if the representative chromaticity is in the defined region of chromaticity values, then establishing driving signals for the broadband light-emitting elements that correspond to the area; and

applying the driving signals to the broadband or primary color light emitting elements that correspond to the area.

18. A method according to claim 17 comprising determining a representative luminance of the area of the image and defining the region of chromaticity values based at least in part on the representative luminance of the area.

19. A method according to claim 17 wherein the display comprises a spatial light modulator comprising an array of controllable pixels, each pixel comprising a plurality of sub-pixels, the method comprising:

estimating a light field at the spatial light modulator, wherein the light field is generated by one or more of the light-emitting elements;

determining a driving signal for each sub-pixel based on a value of the estimated light field at a location of the sub-pixel; and

,

applying the driving signals to the sub-pixels.

20. The method of claim 19 comprising estimating separate light fields for spectral ranges corresponding to each color of the sub-pixels.

21. The method of claim 19 comprising estimating the light field at the spatial light modulator by determining and summing light from individual contributing light-emitting elements for a plurality of locations on the spatial light modulator.

22. A method according to claim 21 wherein estimating the light field comprises determining and summing contributions of light from the individually contributing light-emitting elements based on the driving signal for each such light-emitting element

23. A method according to claim 17 comprising blending light from broadband light-emitting elements with light from primary color light-emitting elements, wherein a ratio of an amount of light from the broadband light-emitting elements to an amount of light from the primary color light-emitting elements is based at least on the representative chromaticity.

24. A method according to claim 23 comprising blending light based at least in part on a size of a MacAdam ellipse for the representative chromaticity, wherein for chromaticities for which the MacAdam ellipse is larger more broadband light is provided than for chromaticities for which the MacAdam ellipse is smaller.